Gear-cutting machine.



C. A. PARSONS, A. Q. CARNEGIE 8; S. S. 00.0K.

' GEAR CUTTING MACHINE,

APPLICAUON FILED MAR. 25, |913.

Patented 31111.18, 1918.

s' SHEETS-snm 9.

r C. A. PARSONS, A. CARN'EGllE-z S. S. COOK.

GEAR CUTTING MACHINE. v APPLlcATlqN man MAR.`25.A1.913.

' Patented Jan. 8, 1918.

6 SHEETS-Snert z.

C. A. PARSONS, A. 0. CARNEGIE & S. S. COO'K.

GEAR CUTTING MAcHzNE.

APPLICATION FILED MAR. 25| 1913.

. 51,252,482, l Patented Jan. 8,1918.

-6 SHEETS-SHEET 3.

ATTORNEYS C. A. PARSNS, A. Q. CARNEGIE & S. S. COOK.

GEAR CUTTING MACHINE.

APPucATl'oN man am. 25. 1913.

1,252,482. I Patented Jan.,8,1918.

6 SHEETS-SHEET 4.

'-c. A. PARSONS, A. 0.,(:ARNEG1E a. s. s. cook.l GEARl CUTTING MACHINE.-APPLICATION FILED MAR. 25| 1913.

Patented Jan. 8,1918.

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,Stanley A5. Com/F',

. '7% 7%. @Maf ATTORNEYS.

X C. A. PARSONS, A. Q. CARNEGIE & S.`S. COOK.l 'GEAR cuT'nNG MACHINE.

APPLICATION FILED MAR. 25.1913.

` framed Jun'. 8,1918.

v 6 SHEETS-SHEET 6.

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larven-reasons ann ALFRED QUINTIN CARNEGIE. or NEWCASTLE; y e., am;saanasysmrggcoox, @aan enema-.semanas ro sam Pensons.

0F WALLSEND, ENGLANB; SAID CABNEGE eneneurams MACHINE.

upon-Tyne, Northumberland, England, and

STANLEY SMITH Coon. of Turbinia -Works, Wallsend-upon-Tyne,Northumberland, Eng-v land, subjects of the King of Great Britain andIreland, have invented certain new and useful Improvements inGear-CuttingMachines, of whichthe following is a specification.

This invention relates to a method of and means for cutting the teeth ingear Wheels, and has for its object to confient such Wheels with ahigher degree ci accuracy than is obtainable with the processes atpresent adopted.

fWhile the present machines cut the teeth with ahigh order of accuracy,a still higher degree of accuracy is desirable to insure the silentoperation of gear wheels when transmitting large powers at high speeds,and also to minimize the wear of the teeth. It is obvious that with theprocesses already adopted the accuracy of the finished wheel cannot begreater than that of the parent gear of the machine by which the teethare cut. Local irregularities in this parent gear cause irregularitiesin the /teeth of the Wheels being cut which exactly correspond inangular position with those of the parent gear, and which, when suchWheels are in operation for the transmission of power, will give rise toperiodic vibrations, often of high frequency, and therefore productiveof noise. In the case, for instance, in which the table on which thework is mounted is rotated by means of a worm and a wormwheel, thelatter being attached permanently to the table, it will .be seen thatthe irregularities formed on the work are a function of the angularposition of the table in relation to the position of the worm. Thelatter 1s usually fixed and since the cutter is also usually in a fixedposition on the machine, andadvances across the work in a directionparallel to the axis of the table. there will result lines ofirregularities on the finished A Specication of Letters Patent.

Application led March 25, 1913. Serial No. 756,762.

wheel lying in planes through the axis of the table, and therefore ofthe work mounted thereon.

It will be seen that irregularities so positloned will, when the Wheelis at work, come `into mesh simultaneously across the face of thewheelthus causing irregularities in the relative rotational motion ofthe Wheel and pinion engaging therewith. If, however, a small amount ofrotary motion relatlve to the table be imparted to the work it willbe-seen that the irregularities formed in the work will be distributedspirally around the Wheel, and that if this relative .creep beconsiderable, these spirals will make a small angle with the plane oflrevolution of the wheel, and will consequently lie closely to eachother, with the result that the pinion and wheel will, when gearedtogether, preserve a constant relative angular velocity between them.

The present invention conslstsfan roviding means for distributing the.irregularities formed in the work in spirals making a comparativelysmall angle with the'plane ofrevolution of said Work, whereby theperiodic correspondence of said irregularities with the irregularitiesof the parent gear rotating the same is destroyed.

The invention also consists in producing a continuous variation in `therelative angular position of the axis of the filial driving member of asystem of gearing imparting motion to the Work and the plane of rotationof the cutter.

The invention further consists in imparting motion to the work by asystem of gear-- ing. the axis of the final driving member of which ismade to revolve slowly about the axis of said work, tberplane of therotation of the cutter being fixed, by which means the irregularitiesformed in the Work are made to lie obliquely, that is, in planes whichdo not pass through the axis of the ivork.

The invention also consists in mounting the Work upon a table having asmall rotary motion relative to the driven member of the parent gearrotating the Work. This rela,- tive rotation may be produced by amovemeut superposed on the rotation of the driven member by a train ofgearing at- Patented Jan. 8, 1918.

4 tached either to said table or to said-driven member, and rotatedtherewith around the axis of the.work,lduring which latter said train ofgearing is itself caused to rotate.

l The invention further consists in the improvements in gear cuttingmachines hereinafter described.

It will be seen that'when the irregularities arise from want of accuracyin the driven member of the parent gear rotating the work, for instance,in the arrangement lusually adopted, the worm, or arise from errors inthe individual teeth of the worm wheel or driven member of the parentgear, such irregularities will be periodic and equal in number to theworm wheel teeth. There will be -in consequence high points on the facesofthe teeth of the finished wheel lying in 'a series of equi-distantlplanes passing through the axis. Between these planes of high pointswill be similar planes of low points. Ifnow the work is given arelativey movement corresponding to half the pitchof the worm wheelteeth, this relativeA movement being effected while the cutter advancesacross the wheel by an amount equal to the feedl per revolution va pointleft high by the cutter at one point will be. practically annulled inthe succeeding revolution and the series of alternate planes of high andlow points respectively will be replaced by a'series of planes of lowpoints. At the same time in planes again intermediate between theseplanes of low points, the cutter retains its correct position forsucceeding revolutions. There will therefore result from such a relativemovement of the work a series of planes of irregularities of double thefrequency and half the amplitude of the original.

, vIt is preferred, therefore, to make the rela- 1 tive motion of thework per revolution ofl the driven member of the parent gear correspondto a fraction of the pitch of the'teeth on such driven member onlyslightly differing from a half, for instance .6 of the pitch V(or 1.6,2.6, etc.

9 Referring now to the accompanying drawings Figure 1 represents a sideview partly in section and partly in elevation of a gear cutting machinein which the present invention is carried into effect. A l

Fig. 2 is a sectional view on the line A-A of Fig.- 1 looking in thedirection of the v arrow, E.

Fig. 3 is a plan view of the machine shown in Fig. 1, the standard forthe cutter being. removed andthe sectionalview being taken on the lineB-B.

Figs. 4 and 5 are two views of amodication. The view in Fig. 4 is asection on the line O -C of Fig. 5, the view shown in Fig. 5 being takenon the line D-Dpf Fig. 4.

Fig. '6 shows a modicatmn in which a train of spur and pinion wheelscarried by a primary table is employed. f

Fig. 7 is a part sectional plan of Fig. 6.

Fig. 8 is a part sectional elevation. of al modification in which atrain of spur and pinion lwheels is employed, carried upon a secondarytable.

Fig. y9 is a part Fig. 8.

Fig. 10 is a part lsectional elevation illustrating a furthermodification in which rotary motion is imparted to the central spindle.

Fig. 11 is a part sectional plan of Fig. 10.

Fig. 12 is a part sectional front elevation showing details of thedriving connections.

According to the arrangement illustrated in Figs. 1- to 3, the gearcuttingmachine is driven by an lelectric motor, a, which vdrives throughsuitable gearing the spindle b, from sectional plan view of which motionis transmitted through suit-1 shaft d. The shaft e is a part of aconnection for shifting reversing gears at g, said shaft being operatedby the hand lever 16". The spindle, b, carries a bevel wheel, z',geara'vertical spindle, lc, mounted in the cutter standard, Z. Thevertical spindle, c, is pro- -ing with another bevel wheel, j,mounted-on vided with afeather-way m, by which its 'rotation istransmitted to the cutter.

The'A spindle,'h, is-p'rovided with a worm, fn, which i engages with aworm wheel, o, on another.

vertical spindle, p, mounted in the cutter standard, lZ. Thisspindle,fp, is threaded, and whenv rotated causes a vertical up or downmovement of the cutter, thus moving the cutter'across the face of thework. The

cutter standard, Z, is provided with suitable means'for being traversedlongitudinally on the bed,g, ofthe machine, by means of the threadedspindle, 1', ,which can be rotated'by the 4hand wheel, s. Theconstruction so far described is of a usual character and formsv no partof thepresent invention.

The rotation of the shaft, cl, istransmit.- f

ted `direct or through suitable compensating' i '120 gear as-shown at23, 24, 25, and as will'be hereinafter described, to a bevel wheel, t,

engaging with another bevel wheel, u, on a .horizontal shaft, a,carrying at its other end another bevel wheel, lw. This engages with`yet a further bevel wheel, on a vertical shaft, y, carrying at itsother end a worm, e, engaging with'a worm Wheel, 1, on a shaft 2,provided with. a worm, 3. This worm, 3, engages with a worm `wheel, 4,-mounted upon a primary table, 5. The worm, 3, and

shown is a secondary table 6, the brackets, 7, preventing the secondarytable from being lifted oithe primary table. Mounted in suitable bearin8, 9, on the primary table, 5, is a spin le, 10,. carrying a worm wheel,11, engaging with a worm, 12, on a spindle, 13, prevented from rotatingby suitable meansA such as the stud, 14. The spindle, 10, also carries as nr wheel,- 15, engaging with'a spur whee 16, mounted upon a secondspindle, 17, supported in the bearing, 9, and carrying at its other enda.'

bevel wheel, 18. This vel wheel engages with a ring of Ateeth 19,v onthe secondary table, 6. The work, 20, is fixed to the secondary table,6, in any convenient manner and in Fig. 1 is shown as a gear wheelhaving two sets of? teeth, 21, 22, the latter of which are .in processof beingl formed by the hob cutter 50. The operation of the arrangementis as follows Motion is imparted in the manner already described to theworm, 3, and from thence to the worm wheel, 4, of the primary table, 5.The spindle, 10, rotates with the rimar table, 5, thus carrying thewormpwiieel, 1 around the worm, 12.l The spindle, 102 is thus caused torevolve, which rotation is'nnparted by the spur wheels, 15, 16, to thespindle, 17, and bevel wheel, 18. In this way the axis of the bevelwheel, 18, is caused to revolve slowly about the axis of the work, 20,thereby giving the secondary table, 6, a rotary movement relative to theprimary table, 5. Thus the work, 20, also has a rotation relative to the,worm wheel, 4. Since the worm, 12, is right handed it will be seen thatthe secondary7 table, 6, will advance relative to the primary table, 5,in whatever direction the latter is in itself rotating.

In this manner the irregularities formed in the work 20, due to theperiodic errors arising from inaccuracy in the worm, 3, or worm wheel,4, forming respectively the driving and driven members of the parentgear rotating the work fall in succeeding revolutions 1n differentangular positions and the resultin irregularities of the finished workare t erefore not periodic, but are distributed in spirals around thework which, if the relative motion of the work, 20, in relation to theworm wheel, 4, is sufficient, will make a small angle with the plane ofrotation of the work, and thus 11e closely to each other. When,therefore, the finished wheel 1s 1n use a constant relative angularveloclty will be preserved between it and the pinion engaging therewith,while the irregularities themselves will tend to wear to a uniformaverage surface. l

It will be understood that the eii'ect of the gearing interposed betweenthe primary table and the work-table is to cause a relative motionbetween them, which motion must bg added to or subtracted from themotion due to the parent gears 3, 4, accordin to whether the gearing isarranged to acce crate or retard the work-table with respect 4to theprimary table.

In order to accommodatev the relative movement between the secondarytable 6 and the worm wheel, 4, without correcting the change speed gearac, when applying the present inventioiA to existing gear cuttingmachines, it is preferable to employ com- ;Siensating gear in the driveto the worm, 3.

uch compensating gear is shown in Figs. 1 and 3, and consists in a spurwheel 23 mounted on the shaft, d, and a second spur wheel, 24, mountedon a shaft which also carries a bevel wheel, t; both the spur wheels, 23and 24, are arranged to engage with a pinion, 25, and since the spurwheels, 23 and 24, are of different size'there will be a relativerotation between the wheels, 23 and 24, and consequently of the shaftson which the are mounted. In this way the speed of the rotation of theworm, 3, can be adjusted to maintain the correct speed of rot-ation ofthe work, 20 with respect to the cutter, in spite of the relativemovement between the secondary table, 6, on which the work is mounted,and the primary table, 5, to which the worm wheel, 4, is attached. Thatis to say by this compensating gearing 23, 24, 25 the speed at which theindex wheel is driven is reduced by the same amount as the speed of theworktable .is increased, thereby preventing the accelerated speed of theworktable relative to the index wheel from having any effect on thehelical twist.

According to the arrangement shown in Figs. 4 and 5, the primary table,5, is dispensed with. The worm wheel, 4, forms a separate element androtates in a groove, 26,

wheel, 18. Anon-rotatable spindle, 13, pro-.-

vided with a worm, 12, which engages the worm wheel, 1l, is alsoprovided..

In a similar way to that. already described;

in connection with the form shown in Figs.

1 to 3, the rotation of the spindle, 10, about' its-own axis due to itsrotation with the table, 6, around the worm, 12, is superposed upon therotation of the worm wheel, 4, thus causing a relative movement betweenthe table, 71, and the worm wheel, 4, the former advancing in thedirection of rotation of the latter since the worm, 12, is .again righthanded. n

vAccording to avfurther form of the invention the fixed spindle 13carries a^ pinion Wheel which 'operates a train ...of spurs 32, 34, 36and 38, and pinions y31, A33, 35 and37 mounted upon the primary table5,\the\ last wheel 38 gearing with an vannular wheel 39" mountedconcentrically upon the secondary table 6. 4 l t.

It will be seen that the movement of-the train o fwheels aboutthe'stationary pinion .30, causes the former to revolve and tooperatenpon the annular wheel 39, attached to the secondary table 6,which is thus given a motion relative to the primary table 5, the amountof such motion `depending upon the proportions adopted in the gearing.

In vva still further form, 'the gearing between the `tables 5 and 6, maybe such'that the train of spur Wheels and pin'ions 31, 32,

" 33, 34, 35,36, 37 and.38, areattached to the secondary table 6, andengage with a circular rack 39 upon the primary table 5. It will furtherbe seenjthat the gearing by I which the relative motion is obtainedinstead .ofbeing operated by engagement with a stationary spindle suchas'the spindle 13,

of the foregoingjmodiications Figs. 1 tog may be operated by othersuitable means for instance through gearing from the' main drive. Forinstance, this central spindle 13 instead of being stationaryv maybegiven a backward rotation vat ten or twenty times the speed of rotationof the work.

. This may beeffected by providing upon the bottom of the spindle 413, aworm wheel 40, engaging a'worm 41 upon a shaft 42,v

l modifications there is produced afcontinuous variation in the relativeangular lposition of thel axis of thel final drivlng member of a systemof gearing imparting motion to the work and the plane ofrevolution-'that is, the plane at right angles to the axls ofrotation-of the cutter.

Havingnow describedour invention, what' upon an., extension of the shaftd.'

we claim as new and desire to secure'by Letters Patent is l 1. A helicalgear hobbing machinecom prising in combination, a worktable, an in# dexwheel, means to rotate said wheel, means actuated by the rotation ofsaid wheel acting to cause rotation of said table at a speed differentfrom said wheel, a hob, means to rotate said hob, means between said hobrotating means and Asaid index wheel rotating means to preserve correctindexing relationv between the rotations ofvsaid hob and the rotation ofsaid table, means to feed said hnb,and means between said'hob feedingmeans and said index wheel rotating means to' preserve correct leadrelation between said hob and said table.

2. In combination, in a helical gear hobbing machine, al hob, toothedindexing means, means for imparting to the work a 'movement relativelyto the indexing means for effecting the distribution of errors about lthe Work, and means foroperating the hob and the indexing'means toobtain indexing and helical lead.

3. In combination, in a helical gear hobbing machine, afhob, toothedindexing means, means for changing the angular relation between a giventooth on the work and a given indexing tooth during the rotation of thework, whereby errors are distributed about thework, andf'neans foroperating'the hob andthe indexing meanslto obtain indexing and helicallead.

bing machine, a work-carrying table, a hob having a traversing movementacross thel work, indexing means including toothed gearing and drivingmeans therefor forv ldriving the table, means for givlng the, in dex-ingmeans an additional movement proportional to the traversing movement ofthe 4. lncombination, in a helical gear hobl ob for obtaining lead, andmeans actuated by said indexing means and actuating said table 'to causethe latter to rotate at a different speed from the indexing means fordistributing errors about the work.

5. In combination, in a helical gear'hobbingmacl1ine,a hob, an indexwheel, a worktable, means for moving the worktable in relation to theindexing wheel to distribute errors about the work, and means vforoperating the indexing wheel a-nd hob for indexing and helical lead, thespeed ,of the index wheel being varied proportionately to the change inspeed of the worktable relative to the indexing wheel to preserve' thedesired lead, substantially as'described.

16. A helical gear bobbing machine, com- A prising in combination, aworktable, an indexwheel, means to rotate said Wheel, means actuated bythe rotation of said wheel and acting to cause rotation of said table ata greater speed than said wheel, a hob, means and' said primary tablerotating means to' to rotate said hob, means to feed said hob, and meansbetween said hob feeding means and said index wheel rotating meanstopreserve correct lead relation between said hob and said-table. y 7. Ahelical gear bobbing machine comprisingl in combination a primary tabe,means to rotate said table, a work carrying secondary table, rotatablymounted upon said primary table, a train of gearing positioned betweenthe two tables and actuated by one of said tables and acting to producerelative motion between them, the axis of the final driving member ofsaid train being caused to revolve about the axis of rotation of theWork'carrying table, a hob, means to rotate said hob, means between saidhob rotating means and said primary table rotatingv means to preservecorrect indexing relation between the rotations of said hob and therotation of said lsecondary table, means to feed said hob, and meansbetween said hob feeding means preserve correct lead relation betweensaid hob and the secondary table.

8, A gear cutting machine comprising, in combination, a primary table,means for rotating the same, a secondary table for supporting the workand'rotatably mounted on the primary table, a center spindle aboutVwhich the primary table turns, a train of v'gearing mounted on theprimary table and l connected at one end with the center spindle and atits other end with the secondary table, said train of gearing beingrotated by the revolutionv of the primary table about the centerspindle, and thereby causing the secondary table to rotate at adifferent rate of speed from the primary table, substantially asdescribed.

t and said table for imparting to said table a constant motion relativetosaid driven member, said relative motion'being dependent only on thedimensions of said gear and independent of the feed of the cutter.

ll. A gear cutting machine comprising a table upon which the workis.mounted, a cutter, means for feeding said cutter, parent gearcomprising driving and driven meinbers rotating said tabie, and meansfor imparting to'the table a constant rotary motion relative to thedriven member of said parent gear andindependent ofthe feed of thecutter.

In testimony whereof, we atlix our signatures in presence of twowitnesses.

CHARLES ALGERNON PARSONS. ALFRED QUINTIN CARNEGIE. STANLEY SMITH 000K.

Witnesses:

CHARLES P. MARTIN, BERTRAM H. MATTHEWS.

